Our own Library of Congress (America's library) has a website that is also a good source of learning. On their site is a vast amount of information. You can easily spend a day going through it and still have a lot to see all that is on it. You also can download and play podcasts and webcasts as well as viewing and downloading photographs from various collections. Informative transcripts and collections can be viewed. There are dedicated sections for kids, librarians publishers and teachers. Certain old newspapers are also available for viewing. There is a lot here related to American History. You also can order at a charge certain videos of historical significance. Simply put there is more than I can ever say in a post of what is here. By going to Thomas.gov which is a part of the Library of Congress you can find legislative information. Status of bills, current activity of the House and Senate, searching the Congressional Record are just some of the things available here.
LibrarySpot.com is largely a reference site. It also is a good gateway through links to other informative sites. It is worth checking out. Again, so much information is at your fingertips. Links to dictionaries, almanacs, calculators, etc, are on this site.
My local library Queens Library has a web site that for starters allows me to reserve books, movies and see the availability of these items at the various branches. My library card allows me to research various databases online including encyclopedias. For example one can get information on companies that they are researching for a job interview or other reason by going to the Business and Company Resource Center available through NOVEL NY which my library is part of. Community information is also available on the Queens Library website.
So if it is 3AM and you cannot get back to sleep and want to do some research head out to the library. The online library.